Improvement in valves for direct-acting engines



VALVES FOR DIRECT-ACTING ENGINES. No.178,465. Patented June 6,1876

N. PETERS. PNOTOL|THOGRAPHER, WASHINGTON, D CA v 2Sheets--ShevetlV E. PURVIS. l

. VALVES FOR DIRECT-ACTING ENGINES. No.1'78,465. Patented .Tune 6,1876'.

N.PETERS, PHOTO-LITHOGRAPHER, WASHINGTON. D C.

. U Nrrnn STATES g PATENT rrron.

vEDWARD PUBVIS, OF NEW YORK, N. Y.

' IMPROVEMENT IN VALVES ,FOR DIRECTACTING ENGINES.

Specification forming part of Letters Patent No. 178,465, dated J une 6, 1876 application filed April 4, 1876.

To all Iwhom it may concern:

Be it known that I, EDWARD PURVIS, of the city, county, and State ot N ew York, have invented certain new and useful Improvements in Valves for Direct-Actin g Engines; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying draw ings, which forms part of this specification.

' This invention consists in a valve for directacting engines, propelled by steam, gas, or other vapor or fluid, but which will here, to simplify explanation, be described as propelled by steam, in which the motion of the engine-piston is made to actuate the valve .which controls said piston without the aid of valve-gear and without the assistance of an vauxiliary valve, by the direct pressure ot' the propelling fluid on the piston controlling valve, as derived in part by the initial pressure of said fluid on said valve, and in part by the spent fluid of the engine-cylinder, as opposed to the reduced pressure of the exhaust. To this end, the piston-controlling valve is constructed with a series of piston-heads of different area and passages in or through said valve, operating in combination with a maininlet, and with passages leading to opposite ends of the engine-cylinder, whereby a dierential pressure .is obtained on the valve, to throw or reverse it by the action of the propelling-duid as the engine-piston reaches the end of its stroke in opposite directions, alternately. The mere form of the valve may be variously changed, as also the arrangement of the passages in or through' it; likewise, the disposition of the main inlet, and of the passages which connect with opposite ends of the e11-4 ginecylinder, without departing' from the characteristic feature or principle of the invention.

Having thus explained the object and nature of the invention, its description will be proceeded with in reference to the accompanying drawings.

Figure lrepresents alongitudinal section of a steam-engine cylinder, with piston therein, and one form of the piston-controlling valve as arranged for operation in parallel relation with the engine-piston. Figs. 2 and 3 are similar Sections of the same, in part, with the engine@ piston and its controlling-valve in ldiirerent positions. Fig. e1E represents a transverse section ot' a steam-engine cylinder, with piston therein,.through the center of the valve-chest, showing another form of the piston-controlling valve as arranged for opera-tion in transverse relation with the engine-piston. Fig. 5 is a similar view, with the valve in a different position; and Fig. 6, a longitudinal View of the engine-cylinder, with the valve-box in section, but having the valve removed. The dotted linen c in Fig. Grepresents the plane in which the sections Figs.'4 and 5 are taken, and the arrows w w the direction in which the same are viewed. A

Referring, in the first instance, to Figs. 1, 2, and 3 ot' the drawing, A is the cylinder of a direct-acting steam-engine, and B its reciprocatin g piston. ('l'is the valve box or chest, ot cylindrical construction on its interior, and fitted with hollow cylindrical heads or ends Cl C2. The steam is admitted to the valve-box C- by means of a central inlet, b, and a longitudinal connecting-passage, c, which opens at its opposite end in to the valve-box within theinner ends of the heads C1 C2. The ordinary or main induction and eduetion passages d d',

which connect with opposite ends of the engine-cylinder, communicate with the valve box or chest near its center. D is the main exhaust-outlet from the valve-chest, which outlet is also central. The induction and eduction passages d d also communicate, near their inner ends, `with the valve-chest, (or,.

rather, with passages through the val\-e,) by backwardly-running passages or branches c e, and, further, connect with the valve-chest by apertures ff in rear or outside of the passages e e', which latter, although here referred to as separate passages or branches, are virtually but extensions or enlargements of the inner ends of the passages d d', and may altogether be omitted by enlarging said inner ends. Independent passages g g connect the interiors of the hollow valve-chest heads G1 C2 with the engine-cylinderat points within the range of the piston B as it completes its stroke in opposite directions, and so that said piston uncovers the same as it approaches the ends of its stroke in either direction. The valve, which is a cylindrical or piston one, is com.

posed, in part, of two main piston-heads or cylindrical body portions, E E', constructed to work in a free but close manner within the body or main portion of the chest C, and arranged at a suitable distance apart, so as to leave themain exhaust-outlet D always exposed between them, where said valve-bodies or piston-heads E E' are connected, by a neck, h, thus causing the space between the pistonheads E E' of the valve to correspond with the exhaust-cavity of a D-shaped slide valve. Furthermore, the valve which is now being described is also composed, in part, of two outer x and smaller heads or pistons, F F', arranged to work in close but free contact within the hollow cylindrical valve-chest heads C102, and connected with the main or larger pistonlieads E E' of the valve by necks M'. These several pistons or piston-heads E E' and F F' of the valve control, respectively, the main induction and eduetion passages d d', their branch passages j' f', and the independent passages g g'. The branch passages e e', conneet, either directly, or by annular cavities k1 k2, around the piston-heads E E' of the'valve, with passages k3 7c, which project longitudinally through the valve, in reverse direction to the ducts d d', into the hollow valve-chest heads G1 G2 in rear of the valves smaller piston-heads F F'.

The operation is as follows: Supposing the parts to be in the position represented in Fig. l, and the engine-piston B to be moving in direction of the arrow x, the steam entering by the inlet b escapes at the one end of the passage c, between the piston-heads E' F', and through the aperture f', which is uncovered by the piston-head E', and, flowing along the passage d', continues yto propel the piston B in direction of the arrow x. rlhe live steam, thus entering by the one end of the passage c, also passes, by the branch e', annular cavity kl, and longitudinal valve-duct 7g4, to the right-hand valve-chest head-C?, in rear ofthe small piston-head F, which then is free from covering the independent passage g, that, prior to the piston B crossing it, had been open to the exhaust in front of said piston, and so exposed the outside face of the larger pistonliead E also to the exhaust, thereby assisting the throw of the valve to the right bythe pressure of the steam on the greater-area of the piston-head E', as against the pressure on the end ofthe piston-head F of less area. At the same time the other main induction and eduction passage d is open to the exhaust vbetween the piston-heads E E' of the valve, and the left-hand valve-chest head (l1 is similarly open to the exhaust in rear of the small piston F', by the branch e, the annular cavity k2, andthe longitudinal Valve-duct 7c3, the small pistonhead F' then covering the independent passage g', and the larger piston-head E closing aperture fand right-hand outlet ofthe passage c. When this is the position of the parts, then there is a differential pressure of the live steam, entering by the inlet b, against the back of the larger piston-head E', as against the live-steam pressure ou the outer end of the small piston-head F, to hold the valve to the right until the engine-piston B, traveling in direction of the arrow x, uncovers, as shown in 2, the independent passage g, when the spent steam of the engine flows through said passage to the back ofthe piston-head E, and counteracts the pressure on the back of the piston-head E', so that the live-steam pressure on back of the small piston-head F starts the valve to the left. This action is continued until the small piston-head F closes the independent passage g, by which time the duet d' will be open to the exhaust, and the live steam will enter by the righthand end of the steam-passage@ and act upon the back ot' the piston-head E, to continue the'throw of the valve tol the left, and to hold it there, as represented in Fig. 3, against the pressure of the steam entering by the duct d, passage e, annular cavity k2, and longitudinal valve-duct 7c3, to the back ot' the small piston-head F', the other small piston F being, at the same time, exposed to the exhaust by the valve-duct 7a4 and passage e', and the outer face of the larger piston-head E' being also exposed to the exhaust by the independent passage g'. This change in the position of the valve causes the engine-piston to be reversed and tocontinue its travel in direction of the throughthe valve in conjunction withl thexed passages, as hereinbet'ore described.

Referring, in the next instance, to Figs. 4, 5, vand 6 of the drawing, which show a modied construction of the valve, and ofthe passages connected with and controlled by it, and represent the -valve as arranged for operation in transverse relation with the engine-piston, A is the engine-cylinder, B its piston, and C its valve-chest, provided with hollow heads O1 C2, as before. rlhe valve itself' is also mainly .of similar construction to that shown in the previous'flgures, and is operated in substantially the same manner; but its larger pistonheads E E', connected by the neck h, are each duplicated or divided transversely, leaving a space in between each Aconnected division of them, into which space the longitudinal passages k3 7a4 through the valve open, said passages extending, as before, through the smaller end piston-heads F F', and lthe necks z' i', which attach them to the larger piston-heads E E'. In this valve, the chest -is supplied with steam by an inlet, b, between the larger piston-heads E E', and connected with 'this piston-head F.

inlet is a longitudinal passage, c c, arranged to branch from either side of said general iiilet, and controlled by the piston-heads E E of the valve. The exhaust-outlet D is also made with a longitudinal extension branching from opposite sides of it, and which is likewise controlled by the piston-heads E E. The main induction and eduction passages d d', which connect the valve-chest with opposite ends of the engine-cylinder, have each duplicate openings into the valve-chest at a suitable distance apart in direction of the travel of the valve, corresponding with the inner end openings and branch passages f f' of the passages d d', in the modification herein tirst described. Furthermore, said induction and eduction passages also have longitudinally and baekwardly branch-ing passages 6 c connected with them at their one opening into the valve-chest, as in the herein previouslydescribed modiiication. There are also independent passages g g', controlled by the smaller piston-heads F F', and connecting the hollow valve-chest heads G1 C2 with the opposite ends or portions ot' the engine-cylinder.

The operation is the same as before. Thus, in Fig. 4:, the valve has been thrown to its extreme position to the right, and is heldin said position by the pressure of the live steam entering by the left-hand branch of the passage c, and acting on the outer face of the larger piston-head E', as against the pressure of steam on the outer end of the smaller piston-head F supplied from the engine-cylinder by the passage d, its branch e', and the longitudinal valve-duct 794. When, however, the enginepiston B, which is supposed to be traveling in direction ofthe arrow z, has passed the passage g it allows steam from behind said piston to act upon the outer face of the larger pistouhead E, and by its counteracting action to the pressure on the outer face of the other larger piston-head E', the valve is started to the right, as shown in Fig. 5, by the pressure of the steam on the back of the smaller pistonhead F until the piston-head E uncovers the right-hand outlet of the live-steam passage c, which admits live steam to` the back ot" the piston-head E to complete the throw of the valve to the right, the piston-head E in the meantime closing the left-hand outlet of the passage c, and opening communication by the passage el, the branch passage e, and the valveduct k3, for steam to enter behind the smaller The motion of the enginepiston having been thus reversed, the valve is held in its extreme position to the right till said piston passes the independent passage g',

when a like action of the valve as before, but in a reverse direction, takes place. rlhe hollow valve-chest heads are alternately exhausted by the valve-ducts k3 and 7a4 being brought l by the movement of the valve alternately in communication with either induction and eduction passage d d open to the exhaust, and with the general exhaust-outlet D, all substantially as hereinbetore explained, with reference to the first-described modification.

To prevent misconception as to the action ofthe various passages, or certain of them, it may here be observed that in both ofthe modications here shown ofthe valve the passages e e are virtually a part ot' the induction and eduction passages d d', and they might altogether be omitted by suitably enlarging or forming the passages d d at such part, and in the modification of the valve shown in Figs. l, 2, and 3 the passages ce', might be extended back to join the branch passages ff, thus makin g one continuous passage of the several passages cl c f or d 6 f. In fact, so t'ar as controlling the motion of the valve is concerned, the passages d d might be enlarged or formed to altogether dispense with the separate passages or branches e e and ff.

I claiml. A valve for controlling and reversing the piston of a direct-acting engine, composed ot', or provided with, duplicate piston-heads at its opposite ends of different areas, and longitudinal ducts passing through the valve and 'connecting the intermediate portion of the valve-chest with the opposite ends thereof', in combination with fixed passages in the valvechest and engine-cylinder, organized substantially as described, whereby the valve is automatically thrown in reverse directions alternately by differential pressure ot' the propelling-duid on the piston-heads of the valve, subject to the control of the engine-piston, essentially as herein set forth.

2. The combination, with the engine-cylinder A and its piston B, of the valve-chest (J, with its hollow ends or heads G1 C2, the valve composed of pistonheads E E and F F ot' different areas, as described, the longitudinal valve-ducts k3 h4, the main induction ports or passages (l d', the-independent passages g g', the steam-inlet b with its longitudinal branch c c, and the exhaust duct or outlet D, substantially as specified.

EDWARD PURVIS.

Witnesses MICHAEL RYAN, FRED, HAYNES. 

